Duncan Racing helps a man dream By the staff of Dirt Wheels, Photos by Pat Carrigan

Pro ATV racer Josh Row was playing like a loon on Danny Franco’s Duncan Racing-modified Suzuki LT500R. It was throwing sand in all directions and throwing itself in the air.

Danny Franco was happy to explain why he contracted Duncan Racing International to get his 1987 Suzuki LT500R “Quadzilla” Quadracer underway: “I’m a stickler for old two-stroke machines, and the Quadzilla is one of the best out there in its class. I could not pass up this opportunity, and I’m glad I didn’t. The build came out beautifully, and the finished machine was more than ready to take on the sand! I decided to go with Duncan Racing to fully redo my Quadzilla due to its extensive knowledge on Suzukis.

The shop in El Cajon is super clean. We discussed what I was looking for, and Loren Duncan made a complete build plan for my ’Zilla. I wanted to relive this Quadracer’s glory days, and boy is that exactly what they did.”

Franco had this to say about the Duncan engine in his monster Suzuki: “We ended up going with the Duncan Racing Paul Turner National engine package, and I’m glad we did because the ’Zilla just flat rips!” Even though the stock Suzuki LT500R is no child’s toy, we can confirm that Franco’s Duncan quad is enormously powerful.

To elevate a monster into a legend requires careful attention and work. It begins with a complete rebuild and refurbishment of the engine, transmission and clutch. DRI rebuilds the crank with a stock rod, replaces all bearings and seals, in addition to blueprinting the transmission.

It would be hard enough to perform a rebuild this comprehensive without the need for a show-quality finish. The cylinder and transmission cases are powdercoated Suzuki blue. All outer engine cases are polished to a brilliant shine. Only then can the engine assembly start. There is no need to refinish the cylinder head. A DRI billet Powerhead replaces the stocker to add power and cooling capability.

Along the way the stock cylinder is treated to Paul Turner Racing porting by Loren Duncan. Paul Turner was a brilliant early pioneer in two-stroke modifications famed for his work with the powerful Honda racing team. Duncan Racing International owns the Paul Turner brand, and DRI has designed and manufactured all PTR products since 1989. Paul Turner Racing exhaust pipes, Fat Boy 2 silencers, Powerhead, and Pyramid reed valves are all proprietary brands of Duncan Racing International.

On some quads it isn’t easy to find a jump in the big dunes at Glamis. That isn’t a problem for Josh Row and a Duncan Racing Suzuki LT500R. It has the power to fly.

Inside the cylinder is a DRI-modified forged piston. After the National kit mods, only the stock airbox and air boot are left of the stock intake or exhaust systems. Inside the airbox is a DR clamp-on air filter kit. It attaches to a pre-jetted Keihin 39mm PWK carburetor that has been treated to a DRI Superflow carburetor mod. Instead of the stock reed valve, the PWK is mounted to a DRI Pyramid reed valve.

With the intake side dialed in, it is time for the exhaust. That consists of a triple-chrome plated PTR exhaust pipe with a gleaming Fat Boy 2 silencer. Two-stroke drool is not allowed on these shiny bits, so the pipe-to-silencer joint is sealed tight with a DRI billet exhaust clamp. The $109.95 billet clamp is a 10-story jump up in function from the rubber sleeve most brands employ. It actually seals the joint.

Not choosing to risk aging stock electrics, DRI modifies the stock flywheel before fitting a brand-new Ricky Stator stator to power the ignition and lights. In addition to clean air, the engine inhales only Sonoco 110 octane race fuel mixed with Maxima 927 two-stroke oil.

Duncan doesn’t need to rebuild any of the clutch parts. Those are all-new Hinson billet parts and a vast improvement over stock. The basket is packed with DRI C25 clutch plates.

This engine doesn’t associate with a ragged chassis. DRI strips the Quadzilla to the frame and repainted, powdercoated, polished, plated and cleaned the entire machine. According to the owner, “It looks better than she did when she was bought off the showroom floor back in 1987!”

The refurbished chassis does include stock A-arms, rear axle, brake calipers and front hubs. It even uses stock footpegs. All the stock parts were polished, plated or painted to look better than new.

Duncan Racing has 20/20 hindsight. It added engine and suspension performance, including a new custom swingarm, but kept Suzuki’s good stuff that was good then and now.


Additional shine comes from a Pacific Plating chromed stock grab bar and DRI chromed front bumper. Interestingly, the stock A-arms have different finishes, The lowers are a powdercoat color called Silver Sparkles and the uppers are chrome. They may not be chrome, but the Elka Stage 4 front shocks look very cool, and they vastly elevate the Quadzilla suspension performance. You may not think so, but a good steering stabilizer can make the suspension feel vastly improved. Knowing that, DRI installed a new GPR V5.

In the rear is a chromoly +2 round-housing swingarm available through DRI. In this case it holds a stock axle, but, like the front, the shock was upgraded to an Elka Stage 4. Hubs are stock in the front and Team in the rear. As we expect from a show-quality machine this clean, it will be a duner for life. It is fitting that the polished DWT red-label wheels have Skat–Trak Mohawks in the front and Skat-Trak eight-paddle Edge tires in the rear.

Braking isn’t that critical in the dunes. Stock calipers are fine, and they are filled with stock pads as well. The brake lines are updated to Crown Series blue braided stainless.

Franco wasn’t going to be crazy about staying with stock, so he opted for the comfort of a Fasst Co. Flexx handlebar. It is fitted with a Motion Pro twist throttle and cables, a Works Connection clutch perch, and ODI grips.

DRI has a clever custom mount for Baja Designs Squadron lights. They blast the dark without adding much weight or ruining the look of the Quadzilla.

A stock fuel tank is fine for dune runs. This one is covered by Maier yellow fenders and a front nose piece. The plastic is refined with a DRI graphics kit. The stock seat is freshened with a Pro Top seat cover. All the custom metal polishing was completed in-house by DRI veteran Jimmy Brown.

Aside from the Elka Stage 4 shocks and premium finishes, much of the front end is as Suzuki built it. It still works just fine. The engine is not quite so stock!


You will never find a Suzuki LT500R in every garage. They were never common, but it does seem like there are more of the first-year 1987 models than other years. When the LT500R was new, it was a time of small-bore sport quads where 250cc two-strokes ruled the dunes. Even compared to those kickstart 250s, the LT500R is a beast. It requires commitment to start it and a talented rider to get the most out of it. And that was then! Compared to a modern 450cc four-stroke sport quad with electric start, the LT500R is a rude and brutish brawler of a quad.

Duncan Racing was able to civilize it in some ways. This LT looks better and handles vastly better than when it was new. It starts readily, and the clutch and shifting are superior to stock.

Then there is the power. With the Skat-Trak paddles and the Duncan performance mods the acceleration is spectacular. Of course, for experienced riders, that is the whole point of a big-bore two-stroke in the dunes. It is more than possible to cruise the dunes on this Quadzilla, but if you want to rip turns with the throttle wide, you must be ready.

Even with a rider as talented as Josh Row at the handlebar, it was wild to see the front end suddenly and violently wheelie mid-slide in a bowl turn. This is not for beginners.

Once you do get it started, you are tingled by vibration and must chase away arm pump from attempting to hold on. On the plus side, there is the sand in your teeth because you can’t keep a smile off your face whenever you twist the throttle on a dune face. It’s a tough job, but we managed for you.

When the original Quadracer-series machine hit, it spelled the end for three-wheelers. Government edicts helped, but that fourth wheel was a huge advantage on the track.


Four-stroke guys will need to learn to give it a little gas while kicking it, and wear motocross boots when you attempt that. Learn it and the engine fires easily as 500cc two-strokes go. Throttle response is crisp and clean as well. The clutch pull is not as easy as modern bikes but is effective. The shifting isn’t as reliable and easy as modern, either. That is sort of the point. With this LT500R you are bringing the past not simply to life but to its best life. The Duncan-modded LT does not disappoint. It is blindingly fast with power that is smooth overall.

Owner Danny Franco rides this legend, so he opted for a Flexx handlebar with modern controls and modern lighting from Baja Designs on a custom Duncan mount..


We found that the stock peg location seemed a little high, but Suzuki had a good grasp of what a quad needed 35 years ago! It is comfortable and easy to move around on. The T-shaped seat Suzuki pioneered remains a standard feature on the best of modern sport quads.

A 2-inch-longer swingarm with a Stage 4 Elka shock in the rear and Stage 4 Elka shocks in the front provide a nice ride in the dunes. Josh Row was grinning like a kid swinging at a pinata as he carved dunes, fought to keep the front end down and leapt into the sky. He had been on his TRX 450R all morning, and he was obviously loving the contrast.

We are happy that this LT500R will stay in the dunes. It is finished to a stunning level, and all that work, time and money should not get beat through the desert or thrashed through laps on a track. For sure it should avoid mud like the Ebola virus. Nice, clean sand is our prescription for the preservation of this bad boy. Plus, dunes are the perfect canvass to make the most of the power.

Lots of Duncan Racing International performance parts went into this build. You could say its silencer is the final part of the power equation.


Duncan Racing was established in 1977, making it a perfect choice to breathe fresh life into a 35-year-old quad. We must agree with owner Danny Franco: “I don’t know who could do it better. Thank you to Duncan Racing for the sweet ride and all the time and effort they put into my build.” And, for those wondering, Franco is happily riding this beauty.

With owner Danny Franco choosing to stay with the stock width and a minimalist show-quality build, this LT500R is light, slim and fast! The embodiment of sport quad.


BAJA DESIGNS: (760) 560-BAJA (2252),

Squadron lights: $449


DR/PTR National midrange engine kit (includes PTR pipe, Fat Boy 2 silencer, PTR/DR National port, Powerhead, Pyramid reed valve, pre-jetted Keihin 39mm PWK carburetor, DR clamp-on air filter kit (goes inside stock air box): $2499

Complete engine, trans, clutch rebuild, HP mods: $695 + parts

PTR Pipe, billet exhaust clamp and Fat Boy 2 Silencer Kit (included in National Kit): $999

Billet exhaust clamp $109.95

Porting by Loren Duncan: $595

PTR billet Powerhead: $299.95

Forged piston w/ DR mod: $179

Pyramid reed valve: $249.95

Crank rebuild by DR: $150 + parts

DR flywheel mod: $105

DR Keihin 39mm PWK: $399

DR Super Flow carb mod: $75

DR clamp-on K&N kit: $149.95

Fuel: Sunoco 110 octane

DR C25 clutch: $209

DR chrome front bumper: $249

Crown Series F brake lines $149.95, Rear $49.95

DR Scott Wilson graphics kit: $175

Pacific Plating chrome (must go through DR, no retail): $750

DR in-house Jimmy Brown polishing: $600

Powder coat frame: $395

Round-housing +2” swingarm: $995

Custom headlight mount (DR) $100


Red label wheels: $109.95, front; $149.95, rear

ELKA SUSPENSION: (800) 557-0552,

Stage 4 front shocks: $1749

Stage 5 rear shock: $1324

FASST COMPANY: (877) 306-1801,

Flexx bar: $399

GPR STABILIZER: (619) 661-0101,

V5 stabilizer: $525

HINSON RACING: (909) 946-2942,

Billet basket: $279.95

MAIER USA.: (530) 272-9036,

Front fender: $353; $337, rear fender; $142, nose piece


MTL Endurance gearbox lube: Varies

927 premix oil: Varies

MOTION PRO: (650) 594-9600,

Throttle cable: $19.95, clutch cable: $22.95

Vortex twist throttle: $54.95


Grips: $23.95

RICKY STATOR: (760) 787-0094,

Hi-output stator: $199

RK EXCEL AMERICA: (760) 732-3161,

520 O-ring chain: $89

SKAT-TRAK: (909) 795-2505,

Mohawks front 21x7x10 tires: $129.95

8-paddle Edge rear 20x11x9 tires: $199.95


13/40 sprockets: $24.95/$28.95


Clutch perch: $149.95

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